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CHEMISTRY SECTION. KEPORT OF B. C. ASTON, F.1.C., F.N.Z.INST., CHIEF CHEMIST. Mineral Content of Pastures Investigation. A notable feature of the year's work has been the extension in the use of limonite as a stock-lick to districts bordering on and even remote from those usually recognized as bush sick, in most cases with spectacular results. In many instances the good results appear to be due to the correcting of a deficiency of iron insufficient to cause acute symptoms of disease, but giving rise to a widespread lowering of production, while in other cases the favourable effects probably follow the tonic effects of iron leading to a suppression of intestinal parasites. Considerations of economy have curtailed the amount of field work that could be undertaken, but by co-operation with officers of other Divisions, notably Veterinarians and Meat Inspectors, a considerable number of samples have been received, especially in connection with the iodine investigation. Pumice Lands. Air-deposited rhyolite pumice, which is the type of volcanic ash associated with bush sickness in the North Island, constitutes the chief soil-forming material over an area of about 8,000 s< | miles, or one-fifth of the total area of the North Island. Bush sickness has so far been found to occur over about half of this area, or more than two and a half million acres. Within the outer boundaries of this proved sick area, however, scattered portions, associated mainly with special topographical features, are relatively healthy. The occurrence of various degrees of pathogenicity is well established, and it is probable that much of the remaining subaerial-pumice country, on large areas of which stockfarming with modern methods has never been attempted, will be found eventually to be affected with bush sickness either in the usual condition or to the extent that treatment with iron licks, such as limonite, will materially increase production. The use of limonite as a lick for preventing and curing bush sickness has now become standard farming practice in the affected districts, and the distribution of the material Ins been taken up by various commercial agencies, among those operating on the largest scale being several of the fertilizer companies. As illustrating the improvement that has taken place, the Supervisor of the Dominion Herd Testing Association writes congratulating the Department, pointing out that where despondency was prevalent a few years ago he found optimism as to the future despite the present low prices. The great success of the experiments would definitely assist the herd testing movement. The Secretary of the Tokoroa Progress League also writes in similar strain, giving instances of the striking results obtained in his district. These include greatly increased cream production as shown by factory returns, the rearing of calves on a large scale, and the deliberate buying-in of sick heifers for curative treatment, thereby securing cheap stock. On one farm the butterfat returns per cow for the same two months of 1931 and 1932 respectively are as follows : — 1981. 1932. No Limonite. Limonite. Lb. per Cow. Lb. per Cow. September .. .. .. .. .. 17 32 October .. .. .. .. .. 24 45 A show is being held in the Tokoroa district this year, a thing unheard of before the introduction of limonite feeding. The output of the Tokoroa cheese-factory, with five less herds supplying milk and with two months and a half still to go, has already eclipsed the previous record. NEED FOR CARE IN LIMONITE PRODUCTION. Disappointing results obtained on several farms, as well as in one departmental experiment, were traced to the use of limonite which was found to be of inferior grade. This product was not from the Whangarei deposit, and on changing over to the previously tested material from that source the trouble was quickly rectified. It is thus evident that field trials should precede the general use of limonite from any new source, and that producers should take care that only stone of the highest quality is ground for stock lick. Grittiness in even a good grade may make the limonite distasteful to sheep. The fineness of an excellent sample of Whangarei limonite recently analysed showed that 83 per cent, of material passed a 200-mesh sieve and that gritty particles were practically absent, everything passing a 60-mesh sieve. SHEEP EXPERIMENTS. The Atiamuri experiment is being continued by breeding from the ewe-hoggets reared last year on limonite. These hoggets are perfectly grown and in splendid condition. Their fleeces at shearing averaged 11-5 lb. of good-quality wool. The wether hoggets have been sent to the works, and could easily be picked out from other sheep with which they were mingled by their superior size. The original ewes, after rearing their second lot of lambs, are being killed for station consumption, the dressed carcass weights being between 80 lb. and 98 lb.

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